Cr-based stainless steel having excellent hydrogen embrittlement resistance

ABSTRACT

A Cr-based stainless steel sheet includes: 0.020 mass % or less of C; 1.00 mass % or less of Si; 1.00 mass % or less of Mn; 0.040 mass % or less of P; 0.0030 mass % or less of S; 10.0 to 18.0 mass % of Cr; 0.020 mass % or less of N; 0.10 mass % or less of Al; and one or both of 0.5 mass % or less of Nb and 0.5 mass % or less of Ti; in which a texture in a sheet surface satisfies (i) and (ii) below. (i) In the sheet surface, an area ratio of crystal grains ({211}±10-degree-oriented grains) whose orientation difference between a normal direction of the surface and a {211}-plane orientation is 10 degrees or less is less than 30%. (ii) For the {211}±10-degree-oriented grains, a length in a rolling direction and a length in a sheet width direction are each less than 0.15 mm on average.

TECHNICAL FIELD

The present invention relates to a Cr-based stainless steel sheet with excellent hydrogen embrittlement resistance, specifically to a Cr-based stainless steel sheet suitable for metals for high pressure hydrogen gaseous equipment.

BACKGROUND ART

In recent years, it has been strongly desired to reduce generation of greenhouse gases mainly including carbon dioxide in order to cope with extreme weather that is partly due to global warming. As part of this move, development of automobiles and transport equipment that use a fuel cell as a power source has been in progress. The fuel cell, which generates electric power by using hydrogen as fuel, does not generate carbon dioxide and achieves high energy conversion efficiency, thereby being regarded as a promising power source.

In the fuel cell using hydrogen as fuel and equipment such as a hydrogen station supplying hydrogen thereto, components are exposed to a hydrogen gaseous environment. In metals exposed to a hydrogen gaseous environment, a phenomenon that mechanical properties such as tensile strength, elongation and drawability decrease due to hydrogen penetrating into the metals is known. This phenomenon is referred to as hydrogen embrittlement. In consideration of the issue of hydrogen embrittlement, Japan Automobile Research Institute, Technical Standard JARIS001 stipulates that austenitic stainless steel SUS316L and an aluminum alloy 6061-T6 should be used for a 35-MPa high-pressure hydrogen tank for automobiles and KHKS0128 stipulates that the austenitic stainless steel SUS316L and the aluminum alloy 6061-T6 should be used for a 70-MPa high-pressure hydrogen tank for automobiles.

Exemplified Standards for High Pressure Gas Safety Act stipulate that materials of austenitic stainless steel sheets (SUS316 and SUS316L) stipulated in JIS G 4304 and JIS G 4305 in which an Ni equivalent (Ni+0.65Cr+0.98Mo+1.05Mn+0.35Si +12.6C) is increased (for instance, the Ni equivalent 28.5) should be used for hydrogen infrastructure equipment with a pressure in a range from 20 MPa to 82 MPa. An operating temperature is in a range from −45 degrees C. to 250 degrees C. For the austenitic stainless steel, for instance, Patent Literature 1 and Patent Literature 2 disclose stainless steel exemplified by SUS316L whose strength is enhanced and whose economic efficiency is improved through a reduction in Mo, which is expensive.

The Safety Regulations for General High-Pressure Gas was amended in 2016 to abolish material restrictions for hydrogen equipment with a pressure of 20 MPa or less. In the wake of easing of the restrictions, there has been an increasingly growing need for using a stainless steel sheet having high economic efficiency even in a high pressure hydrogen gas and also a demand for evaluating various steel materials for hydrogen embrittlement resistance in the high pressure hydrogen gas. Ferritic and martensitic stainless steel sheets (hereinafter, collectively referred to as a “Cr-based stainless steel sheet”) contain almost no Ni (a rare metal) and thus have more excellent economic efficiency than that of the austenitic stainless steel sheets.

Conventionally, for instance, Non-Patent Literature 1 discloses hydrogen embrittlement properties of all steel materials including stainless steel that are evaluated in a high pressure hydrogen gas at room temperature. Typical austenitic stainless steel SUS304 and the Cr-based stainless steel are reported to be prone to hydrogen embrittlement. Accordingly, use of SUS316L and SUS316 is also typically recommended in the high pressure hydrogen gas at a pressure of about 20 MPa. Further, the Cr-based stainless steel having a body-centered cubic structure decreases in toughness at a low temperature (lower than or equal to a room temperature) (i.e., low-temperature embrittlement) as compared with the austenitic stainless steel having a face-centered cubic structure.

A material coated with Al or an Al alloy having excellent hydrogen embrittlement resistance also has been devised in order to obtain more materials usable in the high pressure hydrogen gaseous environment. Patent Literature 3 discloses a pressure tank for high pressure hydrogen gas and high pressure hydrogen gaseous piping, which are coated with Al or an Al alloy. Examples thereof concern formation of a film on the austenitic stainless steel and duplex stainless steel including an austenitic phase but do not disclose formation of a film on a steel material that is prone to hydrogen embrittlement (e.g., the Cr-based stainless steel) and hydrogen penetration properties thereof.

Patent Literature 4 discloses a substrate for hydrogen equipment obtained by: hot-dipping a steel material that is by itself prone to hydrogen embrittlement with the use of an Al-Si alloy added with Si in an amount in a range from 1 to 5%; and forming a hydrogen-impermeable film. The steel material for the substrate is set as carbon steel, low alloy steel or the Cr-based stainless steel, which prevents hydrogen embrittlement and keeps a manufacturing cost low. However, Examples thereof are limited to SUS304, SUS630 (15Cr-4Ni-3Cu) and SCM435 (low alloy steel). Hydrogen embrittlement properties and use of the Cr-based stainless steel sheet having high economic efficiency are also not disclosed.

CITATION LIST Patent Literature(s)

Patent Literature 1: JP 2014-114471 A

Patent Literature 2: JP 2016-183412 A

Patent Literature 3: JP 2004-324800 A

Patent Literature 4: WO 2015-098981

Non-Patent Literature(s)

Non-Patent Literature 1: PVP2007-26820

Non-Patent Literature 2: Michihiko Nagumo, “Fundamentals of Hydrogen Embrittlement”, Uchida Rokakuho (December 2008)

SUMMARY OF THE INVENTION Problem(s) to be Solved by the Invention

The stainless steel described in Patent Literatures 1 to 4 is only austenitic stainless steel, duplex stainless steel and SUS630 (precipitation hardening type). In addition, the Cr-based stainless steel disclosed in Non-Patent Literature 1 is prone to hydrogen embrittlement and thus does not have hydrogen embrittlement resistance for use in the high pressure hydrogen gas. The Cr-based stainless steel also has a problem of the low-temperature embrittlement.

In light of the above circumstances, an object of the invention is to provide a Cr-based stainless steel sheet with excellent hydrogen embrittlement resistance, the Cr-based stainless steel sheet having hydrogen embrittlement resistance for use in a high pressure hydrogen gas and thus being suitable for metals for high pressure hydrogen gaseous equipment. In addition thereto, an object thereof is to achieve low-temperature embrittlement resistance together with hydrogen embrittlement resistance.

Means for Solving the Problem(s)

In order to achieve the above objects, the invention adopts a configuration below.

-   [1] A Cr-based stainless steel sheet including: 0.020 mass % or less     of C; 1.00 mass % or less of Si; 1.00 mass % or less of Mn, 0.040     mass % or less of P; 0.0030 mass % or less of S, 10.0 to 18.0 mass %     of Cr; 0.020 mass % or less of N; 0.10 mass % or less of Al; one or     both of 0.5 mass % or less of Nb and 0.5 mass % or less of Ti, 0 to     0.3 mass % of Sn; 0 to 0.005 mass % of B; 0 to 1 mass % of Ni, 0 to     1 mass % of Cu; 0 to 1 mass % of Mo; 0.2 mass % or less of Sb; 0 to     0.5 mass % of V; 0 to 0.5 mass % of W; 0 to 0.5 mass % of Zr, 0 to     0.5 mass % of Co; 0 to 0.005 mass % of Mg; 0 to 0.005 mass % of Ca;     0 to 0.020 mass % of Ga; 0 to 0.1 mass % of La; 0 to 0.1 mass % of     Y; 0 to 0.1 mass % of Hf; 0 to 0.1 mass % of REM; and a balance     consisting of Fe and impurities, in which a texture in a sheet     surface of the Cr-based stainless steel sheet satisfies (i) and (ii)     below, -   (i) in the sheet surface, an area ratio of crystal grains     (hereinafter referred to as “{211}±10-degree-oriented grains”) whose     orientation difference between a normal direction of a surface of     the steel sheet and a {211}-plane orientation is 10 degrees or less     is less than 30%, and -   (ii) for the {211}±10-degree-oriented grains defined in (i), a     length in a rolling direction and a length in a sheet width     direction are each less than 0.15 mm on average. -   [2] The Cr-based stainless steel sheet according to the invention,     further including 0.001 to 0.3 mass % of Sn and 0.005 mass % or less     of B, in which the Cr-based stainless steel sheet satisfies     Formula (1) below,

Si+0.5 Mn+10 P+5 Nb+2 Ti<2.00   Formula (1),

where in the formula, symbols of elements indicate contents (mass %) of the respective elements.

-   [3] The Cr-based stainless steel sheet according to the invention,     further including one or more selected from 1 mass % or less of Ni,     1 mass % or less of Cu, 1 mass % or less of Mo, 0.2 mass % or less     of Sb, 0.5 mass % or less of V, 0.5 mass % or less of W, 0.5 mass %     or less of Zr, 0.5 mass % or less of Co, 0.005 mass % or less of Mg,     0.005 mass % or less of Ca, 0.020 mass % or less of Ga, 0.1 mass %     or less of La, 0.1 mass % or less of Y, 0.1 mass % or less of Hf,     and 0.1 mass % or less of REM. -   [4] The Cr-based stainless steel sheet according to the invention,     in which the Cr-based stainless steel sheet is used for metals for     high pressure hydrogen gaseous equipment.

According to the invention, a Cr-based stainless steel sheet having excellent low-temperature toughness together with excellent hydrogen embrittlement resistance can be provided. Further, the Cr-based stainless steel sheet according to the invention can be suitably used for metals for the high pressure hydrogen gaseous equipment.

DESCRIPTION OF EMBODIMENT(S)

In order to achieve the above objects, the inventors have intensely studied an influence of alloy elements and a texture on hydrogen embrittlement resistance and low-temperature embrittlement resistance in a Cr-based stainless steel sheet, thereby obtaining the following novel findings to arrive at the invention.

(a) As described above, properties required for metals for high pressure hydrogen gaseous equipment are hydrogen embrittlement resistance and low-temperature embrittlement resistance. For a Cr-based stainless steel sheet, a hydrogen amount to penetrate into a steel material from a high pressure hydrogen gas reduces because of a crystal structure thereof as compared with that of an austenitic stainless steel sheet. However, a Cr-based stainless steel sheet having hydrogen embrittlement resistance suitable for use in a high pressure hydrogen gas has not been obtained. According to Non-Patent Literature 2, hydrogen embrittlement is characterized as a decrease in mechanical properties (strength, elongation and drawability) which plastic deformation involves. Accordingly, hydrogen embrittlement is a phenomenon that a fracture of the metals progresses due to an interaction between hydrogen penetrating into the steel material from the high pressure hydrogen gas and plastic deformation. From recent research results, Hydrogen-Enhanced Strain-Induced Vacancy Theory, which states that the interaction between hydrogen and plastic deformation promotes generation of vacancy-type lattice defects in the steel to progress the fracture, is considered as reliable in explaining a mechanism of hydrogen embrittlement (Non-Patent Literature 2). Accordingly, in order to achieve the Cr-based stainless steel sheet suitable for use in the high pressure hydrogen gas, there is a need for reducing the interaction between hydrogen and plastic deformation to the extent possible. In particular, since Cr has high hydrogen trapping capability, the Cr amount is reduced to 18% or less in the invention. Further, the inventors have found that added amounts of Si, Mn, P, Ti and Nb are preferably controlled to be in respective predetermined ranges.

(b) The inventors further have found that when a slow strain rate tensile test is performed in the high pressure hydrogen gas, a crystal orientation influences generation of cracks caused by the interaction between hydrogen and plastic deformation. When hydrogen embrittlement becomes apparent, the cracks frequently are generated or develop from an inside of crystal grains. It has been found that the cracks in the crystal grains are often generated in a rolling texture in a form of {211}-oriented grains (crystal grains where a {211}-plane orientation is in a normal direction of a surface of the steel sheet), not in a recrystallization texture in a form of {111}-oriented grains (crystal grains where a {111}-plane orientation is in the normal direction of the surface of the steel sheet). From these facts, it is presumed that strains are likely to be introduced to and accumulated in the {211}-oriented grains due to the interaction between hydrogen and plastic deformation. It is speculated that the generation of the vacancy-type lattice defects is activated, so that the {211}-oriented grains act as sites of crack generation. In order to suppress hydrogen embrittlement that progresses in such a mechanism, it is effective not only to adjust respective ranges of the above alloy elements but also to reduce an area ratio and a size of the {211}-oriented grains, and thresholds of the area ratio and the size have been found.

(c) Hydrogen penetrating into the steel material from the high pressure hydrogen gas transfers along a grain boundary acting as a main diffusion path. Addition of a minute amount of Sn and B, which are grain boundary segregation elements, forms a diffusion barrier at the grain boundary with hydrogen, thereby reducing the interaction between hydrogen and plastic deformation. In a conventional Cr-based stainless steel, impurity elements such as P and S segregate at the grain boundary, thereby tending to promote low-temperature embrittlement. Accordingly, the inventors have focused on the addition of a minute amount of Sn and B and have found that these elements are contained in respective predetermined ranges to suppress an adverse effect of P, S and the like, thereby likely achieving both hydrogen embrittlement resistance and low-temperature embrittlement resistance.

A summary of the invention achieved on the basis of the above findings (a) to (c) is as follows.

A Cr-based stainless steel sheet according to an exemplary embodiment is a Cr-based stainless steel sheet with excellent hydrogen embrittlement resistance and low-temperature embrittlement resistance, the Cr-based stainless steel sheet including: 0.020 mass % or less of C; 1.00 mass % or less of Si; 1.00 mass % or less of Mn; 0.040 mass % or less of P; 0.0030 mass % or less of S, 10.0 to 18.0 mass % of Cr; 0.020 mass % or less of N; 0.10 mass % or less of Al; one or both of 0.5 mass % or less of Nb and 0.5 mass % or less of Ti; and a balance consisting of Fe and impurities, in which a texture in a sheet surface of the chromium stainless sheet satisfies (i) and (ii) below.

-   (i) In the sheet surface, an area ratio of crystal grains     ({211}±10-degree-oriented grains) whose orientation difference     between a normal direction of a surface of the steel sheet and a     {211}-plane orientation is 10 degrees or less is less than 30%. -   (ii) For the {211}±10-degree-oriented grains defined in (i), a     length in a rolling direction and a length in a sheet width     direction are each less than 0.15 mm on average.

It is preferable that the Cr-based stainless steel sheet according to the exemplary embodiment further contains 0.001 to 0.3 mass % of Sn and 0.005 mass % or less of B, and satisfies Formula (1) below.

Si+0.5 Mn+10 P+5 Nb+2 Ti<2.00   Formula (1)

In the above formula, symbols of elements indicate contents (mass %) of the respective elements.

The Cr-based stainless steel sheet according to the exemplary embodiment may further contain one or more selected from 1 mass % or less of Ni, 1 mass % or less of Cu, 1 mass % or less of Mo, 0.2 mass % or less of Sb, 0.5 mass % or less of V, 0.5 mass % or less of W, 0.5 mass % or less of Zr, 0.5 mass % or less of Co, 0.005 mass % or less of Mg, 0.005 mass % or less of Ca, 0.020 mass % or less of Ga, 0.1 mass % or less of La, 0.1 mass % or less of Y, 0.1 mass % or less of Hf, and 0.1 mass % or less of REM.

It is preferable that the Cr-based stainless steel sheet according to the exemplary embodiment is used for metals for high pressure hydrogen gaseous equipment.

Elements of the invention will be described in detail below. It should be noted that an indication “%” for contents of elements means “mass %”.

C is 0.020% or less.

C increases work-hardening of steel through solid-dissolution thereof and precipitation of carbides to deteriorate hydrogen embrittlement resistance. C further decreases toughness to deteriorate low-temperature embrittlement resistance.

Accordingly, the C content is preferably as small as possible and thus has an upper limit of 0.020% or less. However, a reduction in the C content requires a complex refining process, thereby resulting in an increase in cost. Accordingly, the C content is preferably 0.001% or more. In view of the refining cost in addition thereto, the C content is preferably in a range from 0.003 to 0.015%, more preferably in a range from 0.003 to 0.010%.

Si is 1.00% or less.

Si is an effective deoxidizing element. However, excessive addition of Si increases solid solution strengthening and work-hardening, thereby resulting in a reduction in hydrogen embrittlement resistance and low-temperature embrittlement resistance. Accordingly, an upper limit of the Si content is set at 1.00% or less. In order to ensure deoxidation capability, a lower limit of the Si content is preferably 0.01% or more. In view of productivity and properties, the Si content is preferably in a range from 0.05 to 0.50% and may be in a range from 0.05 to 0.30%.

Mn is 1.00% or less.

Mn is an effective deoxidizing element and also an element effective in achieving low-temperature embrittlement resistance through improvement in toughness by fixing S. However, excessive addition of Mn increases work-hardening, thereby resulting in a reduction in hydrogen embrittlement resistance and low-temperature toughness. Accordingly, an upper limit of the Mn content is set at 1.00% or less. In order to ensure a deoxidation effect and a fixing effect for S, a lower limit of the Mn content is preferably 0.01% or more. In view of effects and productivity, the Mn content is preferably in a range from 0.05 to 0.50% and may be in a range from 0.05 to 0.30%.

P is 0.040% or less.

P is an element reducing low-temperature embrittlement resistance through grain boundary segregation. Accordingly, the P content is preferably as small as possible, and thus has an upper limit of 0.040% or less. However, an excessive reduction in the P content results in an increase in a refining cost. Accordingly, a lower limit of the P content is preferably 0.005% or more. In view of production cost and properties, the P content is more preferably in a range from 0.010 to 0.030% and may be in a range from 0.010 to 0.020%.

S is 0.0030% or less.

S deteriorates low-temperature embrittlement resistance through grain boundary segregation and formation of sulfides in steel. Accordingly, the S content is preferably as small as possible, and thus has an upper limit of 0.0030% or less. However, an excessive reduction in the S content results in an increase in material and refining costs. Accordingly, a lower limit of the S content is preferably 0.0001% or more. In view of production cost and properties, the S content is more preferably in a range from 0.0002 to 0.0015% and may be in a range from 0.0002 to 0.0008%.

Cr is 10.0 to 18.0%.

Cr is a basic element in the Cr-based stainless steel according to the exemplary embodiment and is also an essential element for maintaining hydrogen embrittlement resistance and low-temperature embrittlement resistance in addition to corrosion resistance of the steel. In order to obtain the above properties on the assumption that the steel according to the exemplary embodiment is used in a high pressure hydrogen gas, a lower limit of the Cr content is set at 10.0% or more. In order to achieve both hydrogen embrittlement resistance and low-temperature embrittlement resistance, an upper limit of the Cr content is set at 18.0% or less.

More than 18.0% of Cr, which has high hydrogen trapping capability, increases a hydrogen amount to penetrate into the steel from a high pressure hydrogen gaseous environment to deteriorate hydrogen embrittlement resistance and sometimes causes the texture to fall outside the preferable ranges of the invention. The Cr content may be more preferably 11.0 or more and less than 17.0% or in a range from 12.0 to 15.0%.

N is 0.020% or less.

Similarly to C, N increases work-hardening of steel through solid dissolution thereof and precipitation of carbides to deteriorate hydrogen embrittlement resistance.

Further, N decreases toughness to deteriorate low-temperature embrittlement resistance. Accordingly, the N content is preferably as small as possible and thus has an upper limit of 0.020% or less. However, a reduction in the N content requires a complex refining process, thereby resulting in an increase in cost. Accordingly, the N content is preferably 0.001% or more. In view of properties and production cost, the N content is preferably in a range from 0.005 to 0.015%.

Al is 0.10% or less.

Al is a highly effective deoxidizing element. However, Al decreases toughness of steel to deteriorate low-temperature embrittlement resistance and sometimes causes the texture to fall outside the preferable ranges of the invention. Accordingly, an upper limit of the Al content is set at 0.10% or less. In view of a deoxidation effect, a lower limit of the Al content is preferably 0.005% or more. In view of properties and productivity, the Al content is preferably in a range from 0.01 to 0.07% and may be in a range from 0.01 to 0.05%.

One or both of 0.5% or less of Nb and 0.5% or less of Ti

Nb and Ti segregate at a grain boundary to suppress grain boundary segregation of P and S, thereby improving low-temperature embrittlement resistance. Further, Nb and Ti are also likely to improve hydrogen embrittlement resistance by preventing work-hardening of steel by functioning as stabilizing elements for fixing C, N, P and S. Nb and Ti both exhibit these two functions and thus are elements effective in improving hydrogen embrittlement resistance and low-temperature embrittlement resistance, which are the object of the invention. When Nb and Ti are contained, the Nb and Ti contents are each preferably 0.01% or more in order to exhibit the effects. However, excessive addition of Nb and Ti increases work-hardening, thereby resulting in a reduction in hydrogen embrittlement resistance or an increase in alloy cost. Further, the excessive addition of Nb and Ti decreases toughness and sometimes causes the texture to fall outside the preferable ranges of the invention. Accordingly, an upper limit of each of the Nb and Ti contents is set at 0.5% or less. In view of the effect of improving the properties and the alloy cost, a total content of one or both of Nb and Ti is preferably in a range from 0.05 to 0.5%.The total content of one or both of Nb and Ti is more preferably in a range from 0.08 to 0.4% and may be 0.1 to 0.3%.

The Sn and B contents are further preferably in respective ranges below.

Sn is 0.001 to 0.3%.

Sn is an effective element for improving hydrogen embrittlement resistance and low-temperature embrittlement resistance, which are the object of the invention. Sn, which is a grain boundary segregation element, forms a diffusion barrier at a grain boundary with hydrogen, thereby reducing an interaction between hydrogen and plastic deformation. Further, Sn suppresses segregation of P and S at a grain boundary to alleviate an adverse effect of low-temperature embrittlement resistance. The Sn content being in a predetermined range is likely to achieve both hydrogen embrittlement resistance and low-temperature embrittlement resistance. Accordingly, the Sn content is preferably in a range from 0.001 to 0.5% in the invention. 0.001% or more of Sn is to be contained to exhibit the above effects, thereby improving hydrogen embrittlement resistance. However, excessive addition of Sn increases a Sn concentration at a grain boundary to reduce low-temperature embrittlement resistance and productivity. Accordingly, an upper limit of the Sn content is set at 0.5% or less. The Sn content is preferably in a range from 0.005 to 0.3% and may be in a range from 0.010 to 0.2%.

B is 0.005% or less.

B is a grain boundary segregation element and is also an element for improving hydrogen embrittlement resistance and low-temperature embrittlement resistance similarly to Sn. Accordingly, it is effective to contain B in the Cr-based stainless steel according to the exemplary embodiment. In order to improve hydrogen embrittlement resistance properties, the B content is preferably 0.0003% or more in the invention. However, excessive addition of B results in a reduction in elongation or productivity. Accordingly, an upper limit of the B content is set at 0.005% or less. The B content is preferably in a range from 0.0005 to 0.002% and may be in a range from 0.001 to 0.002%.

It is preferable that Si, Mn, P, Nb and Ti are contained in the above respective ranges and further satisfy Formula (1) below in order to improve hydrogen embrittlement resistance and low-temperature embrittlement resistance, which are the target of the invention.

Si+0.5 Mn+10 P+5 Nb+2 Ti<2.00   Formula (1)

In the above formula, symbols of elements indicate contents (mass %) of the respective elements.

In order to improve the above properties (the object of the invention), it is preferable that the left side of Formula (1) is less than 2.00 and a lower limit thereof is 0.05 in terms of properties and productivity. The left side of Formula (1) is preferably in a range from 0.35 to 1.80, more preferably in a range from 0.50 to 1.50.

In addition to the above elements, Fe and impurities are contained. However, elements described below can be optionally contained in addition to the above elements as long as effects achieved by the technical features of the invention are not impaired. Reasons for limitation of the content thereof will be described below. A lower limit of each of the elements described below is 0%.

Ni is 1% or less.

Cu is 1% or less.

Mo is 1% or less.

Ni, Cu and Mo are elements effective in improving corrosion resistance. Ni and Cu are also effective in improving low-temperature toughness. In order to exhibit these effects, Ni, Cu and Mo may be each contained at 0.05% or more. Excessive addition thereof increases solid solution strengthening and work-hardening of stainless steel, resulting in a reduction in hydrogen embrittlement resistance. Accordingly, an upper limit of each of the Ni, Cu and Mo contents is set at 1% or less.

The Ni, Cu and Mo contents are each more preferably in a range from 0.1% to 0.8%, further preferably in a range from 0.2% to 0.5%.

Sb is 0.2% or less.

V is 0.5% or less.

W is 0.5% or less.

Zr is 0.5% or less.

Co is 0.5% or less.

Sb, V, W, Zr and Co are elements effective in improving corrosion resistance and also improving low-temperature embrittlement resistance by suppressing grain boundary segregation of P and S, and thus are contained as required. In particular, Sb is a strong grain boundary segregation element and has an effect of blocking grain boundary segregation of impurity elements such as P and S similarly to Sn and B. When Sb, V, W, Zr and Co are contained, the Sb, V, W, Zr and Co contents are each preferably 0.01% or more in order to exhibit the effects. Since excessive addition thereof reduces productivity and low-temperature embrittlement resistance, the Sb content is set at 0.2% or less and V, W, Zr and Co are each set at 0.5% or less. The

Sb content is more preferably in a range from 0.02 to 0.15%, further preferably in a range from 0.02 to 0.1%.The V, W, Zr and Co contents are each more preferably in a range from 0.02 to 0.3%, further preferably in a range from 0.02 to 0.2%.

Mg is 0.005% or less.

Mg acts as a deoxidizer by forming an Mg oxide with Al in molten steel and also as a crystallization nucleus of TiN. Since TiN becomes a solidification nucleus of a ferrite phase in a solidification process, Mg facilitates crystallization of TiN to finely generate the ferrite phase in solidification. Refinement of a solidified structure also can improve low-temperature embrittlement resistance. When Mg is contained, the Mg content is preferably 0.0001% or more in order to exhibit the effects. However, since more than 0.005% of Mg deteriorates productivity and corrosion resistance, an upper limit of the Mg content is set at 0.005% or less. The Mg content is preferably in a range from 0.0003 to 0.002%, further preferably in a range from 0.0003 to 0.001%.

Ca is 0.005% or less.

Ga is 0.020% or less.

Ca and Ga are elements for improving cleanliness of steel and are contained as required in order to suppress an increase in work-hardening and thereby increase hydrogen embrittlement resistance. When Ca and Ga are contained, the Ca and Ga contents are each preferably 0.0003% or more in order to exhibit the effects. However, excessive addition of Ca and Ga results in a reduction in productivity and corrosion resistance. Accordingly, an upper limit of the Ca content is set at 0.005% or less and an upper limit of the Ga content is set at 0.020% or less. It is preferable that the Ca content is in a range from 0.0003 to 0.0030% and the Ga content is in a range from 0.0030 to 0.015%.

La is 0.1% or less.

Y is 0.1% or less.

Hf is 0.1% or less.

REM is 0.1% or less.

La, Y, Hf and REM are elements for improving cleanliness of steel similarly to Ca and Ga and may be contained as required in order to suppress an increase in work-hardening and thereby increase hydrogen embrittlement resistance. When La, Y, Hf and REM are contained, the La, Y, Hf and REM contents are each preferably 0.001% or more in order to exhibit the effects. However, excessive addition of La, Y, Hf and REM results in an increase in alloy cost and a reduction in productivity. Accordingly, an upper limit of the La, Y, Hf and REM contents are each set at 0.1% or less. The La, Y, Hf and REM contents are each preferably in a range from 0.001 to 0.05%, further preferably in a range from 0.001 to 0.03%.

Specifically, REM (rare-earth elements) collectively refers to two elements of scandium (Sc) and yttrium (Y); and fourteen elements (lanthanoid) from cerium (Ce) to lutetium (Lu) in the periodic table. These elements may be contained alone or may be contained in a form of a mixture.

It should be noted that impurities contained in the balance mean components mixed from ores or scraps used as a material or due to a manufacturing environment in industrially manufacturing steel, which are acceptable as long as the objects of the invention can be achieved. 0.1% or less of Ta, 0.01% or less of Bi, 0.05% of Zn and 0.0005% or less of H may be contained as required. The Cr-based stainless steel according to the exemplary embodiment contains ferrite crystal grains and further may contain martensite crystal grains.

Next, the texture of the Cr-based stainless steel sheet according to the exemplary embodiment will be described. The texture in the sheet surface of the chromium stainless sheet according to the exemplary embodiment satisfies (i) and (ii) below.

-   (i) In the sheet surface, an area ratio of crystal grains     ({211}±10-degree-oriented grains) whose orientation difference     between a normal direction of the surface of the steel sheet and a     {211}-plane orientation is 10 degrees or less is less than 30%. -   (ii) For the {211}±10-degree-oriented grains defined in (i), a     length in a rolling direction and a length in a sheet width     direction are each less than 0.15 mm on average.

The {211}-plane orientation refers to a normal direction of the {211}-plane.

The {211} orientation is referred to as an a-fiber, which is a rolling texture aggregated through cold-rolling. According to the invention, it has been found that it is effective to control, in the sheet surface, the area ratio and a size of the {211}±10-degree-oriented grains, which are frequently sites of crack generation, in order to improve hydrogen embrittlement resistance. The area ratio of the {211}±10-degree-oriented grains is set at less than 30% and an abundance ratio of a recrystallization texture in a form of a {111} orientation is increased in the sheet surface, thereby contributing to improving hydrogen embrittlement resistance. The area ratio of the {211}±10-degree-oriented grains is preferably in a range from 5 to 20%, more preferably in a range from 3 to 15% in terms of hydrogen embrittlement resistance and productivity.

In the sheet surface, the size of the {211}±10-degree-oriented grains is set such that the length in the rolling direction and the length in the sheet width direction (rolling vertical direction) are each less than 0.15 mm on average. A reduction in the size of the {211}±10-degree-oriented grains reduces introduction of strains to and accumulation of the strains in the {211}±10-degree-oriented grains, thereby contributing to improving hydrogen embrittlement resistance. The size of the {211}±10-degree-oriented grains is preferably less than 0.10 mm, more preferably less than 0.07 mm in terms of hydrogen embrittlement resistance and productivity.

In the invention, the “sheet surface” refers to regions reaching at most t/8 of a thickness t of the steel sheet, i.e., regions on respective two sides of the steel sheet reaching at most a thickness 1/8t from the respective surfaces of the steel sheet in a surface direction. In the sheet surface, the {211}±10-degree-oriented grains refer to crystal grains having a crystal orientation whose orientation difference between the normal direction of the surface of the steel sheet and the {211}-plane orientation is 10 degrees or less.

The texture can be analyzed using electron backscatter diffraction (hereinafter, EBSD). EBSD rapidly measures and analyzes the crystal orientation of each of the crystal grains in a microregion of a sample surface. Regarding a crystal orientation group contributing to hydrogen embrittlement resistance, the area ratio and the grain size of the {211}±10-degree-oriented grains can be quantified by displaying a crystal orientation map of the crystal orientation group divided into the {211}±10-degree-oriented grains and other regions in the sheet surface. For instance, in a plane reaching at most t/8 of the thickness t of the steel sheet from the surface of the steel sheet and being parallel to the surface of the steel sheet, a measurement region (sheet width direction: 850 μm, rolling direction: 2250 μm) is subjected to EBSD measurement at a magnification of 100 to display the crystal orientation map of the crystal grains (i.e., the {211}±10-degree-oriented grains) whose orientation difference between the normal direction of the plane parallel to the surface of the steel sheet and the {211}-plane orientation is 10 degrees or less, whereby the area ratio and the grain size (in the rolling direction and the sheet width direction) thereof can be quantified. When regions reaching at most t/8 of the thickness t of the steel sheet from the surface of the steel sheet are defined as an inspection surface, the texture in the sheet surface can be reproducibly evaluated.

The hydrogen embrittlement resistance is evaluated by a slow strain rate tensile test for which a relatively slow strain rate is used. The strain rate is preferably 10⁻⁵/s. When the strain rate is relatively large, i.e., 10⁻⁴/s or more, penetration and diffusion of hydrogen into the steel do not progress, sometimes resulting in a reduction in hydrogen embrittlement of the steel. In contrast, when the strain rate is small, i.e., 10⁻⁶/s, excessive test time is required and the effect of the strain rate to hydrogen embrittlement properties is saturated. The hydrogen embrittlement resistance is evaluated for tensile strength and fracture elongation in the slow strain rate tensile test. It is more favorable that a value of the tensile strength and the fracture elongation in the high pressure hydrogen gas is more unlikely to be lowered as compared with the value thereof in an atmosphere or in an inert gas. Here, a value obtained by dividing the tensile strength in the high pressure hydrogen gas by the tensile strength in the atmosphere or in the inert gas is referred to as a “relative tensile strength”. A value obtained by dividing the fracture elongation in the high pressure hydrogen gas by the fracture elongation in the atmosphere or in the inert gas is referred to as a “relative elongation”. For the Cr-based stainless steel sheet according to the exemplary embodiment, it is preferable that the relative tensile strength is 0.98 or more and the relative elongation is 0.75 or more. It is more preferable that the relative tensile strength is in a range from 0.98 to 1.05 and the relative elongation is a range from 0.85 to 1.05.

The low-temperature embrittlement resistance is evaluated by a Charpy impact test according to JIS Z 2242. For instance, a 2-mm-thick test piece having a V-notch shape is used to measure absorption energy. The low-temperature embrittlement resistance is evaluated in terms of an energy transition temperature according to Annex D of JIS. A lower energy transition temperature is more favorable. The energy transition temperature refers to a temperature corresponding to a half value of the absorption energy at a temperature at which a fracture rate due to a ductile fracture is 100%.The energy transition temperature is preferably −10 degrees or less in terms of use of the Cr-based stainless steel sheet according to the exemplary embodiment for outdoor and on-vehicle hydrogen equipment. The energy transition temperature is more preferably −40 degrees or less in terms of the use thereof in a cold region.

Next, a manufacturing method of the Cr-based stainless steel sheet according to the exemplary embodiment will be described.

When the Cr-based stainless steel sheet according to the exemplary embodiment satisfies the above chemical composition, the hydrogen embrittlement resistance and low-temperature embrittlement resistance (the object of the invention) sometimes can be ensured even if typical process conditions such as casting, hot-rolling and cold-rolling are used for manufacturing thereof.

It is preferable that the Cr-based stainless steel sheet according to the exemplary embodiment satisfies the above chemical composition and manufactured by the following method in order to improve the hydrogen embrittlement resistance by forming the texture of the invention.

It is preferable that the steel having the above chemical composition is hot-rolled, annealed after the hot-rolling at a temperature of 900 degrees C. or less, subsequently cold-rolled at a rolling reduction rate of 40% or more, and is subjected to finish annealing at a temperature of more than 900 degrees C. The heat treatment after the hot-rolling (annealing after the hot-rolling) is preferably performed at a temperature of 900 degrees C. or less, more preferably in a temperature range from 700 to 900 degrees C. in order to suppress a growth of the {211}-oriented grains, which are generated at the hot-rolling stage.

The cold-rolling may be performed by a reversible 20-stage Sendzimir rolling mill, a 6 or 12-stage rolling mill, ora tandem rolling mill configured to continuously roll a plurality of passes. In order to form the texture of the invention, a larger work roll diameter is preferable. Accordingly, the work roll diameter is preferable 200 mm or more. Rolling with such a large-diameter roll is preferably performed in a primary cold-rolling (initial cold-rolling in a case where plural times of cold-rolling are repeatedly performed). The cold-rolling grows the recrystallization texture in a form of the {111}-oriented grains to reduce the area ratio of the rolling texture in a form of the {211}±10-degree-oriented grains, thereby being effective in forming the target texture of the invention. The cold-rolling is preferably performed at a rolling reduction rate of 40% or more. When the cold-rolling rate is less than 40%, the area ratio and the size of the {211}±10-degree-oriented grains in the recrystallization texture are likely to increase, sometimes resulting in a reduction in the hydrogen embrittlement resistance. The rolling reduction rate is preferably in a range from 40 to 90%, more preferably in a range from 50 to 80% in terms of the hydrogen embrittlement resistance and the productivity.

The finish annealing after the cold-rolling is preferably performed through the heat treatment at a temperature of more than 900 degrees C. in order to reduce the area ratio and the size of the {211}-oriented grains by growing the {111}-oriented grains. Since an excessive temperature rise increases the size of the {211}±10-degree-oriented grains through the crystal grain growth, an upper limit of a finish annealing temperature is preferably 1050 degrees C. An atmosphere for the finish annealing is not particularly defined but preferably an atmospheric air, an LNG fuel atmosphere and a BA atmosphere.

A soaking time for the heat treatment (finish annealing) is preferably in a range from 10 seconds to 10 minutes. The soaking time is preferably 10 seconds or more in order to soften a material for the cold-rolling. When the soaking time is 10 minutes or less, the texture effective for the hydrogen embrittlement resistance can be ensured by suppressing the growth of the {211}±10-degree-oriented grains to reduce the size of the crystal grains.

EXAMPLE(S)

Example(s) of the invention will be described below.

TABLE 1 Chemical Composition (Mass %), Balance: Fe and Impurities C Si Mn P S Cr N Al Nb Ti Sn B Formula (1) Others A 0.019 0.93 0.01 0.016 0.001  12.1 0.018 0.011 0.13 0.14 0.00 0.00 2.03 B 0.006 0.08 0.07 0.038 0.0005 11.6 0.008 0.089 0.00 0.46 0.00 0.00 1.42 Mg: 0.002, Ca: 0.0012, Ga: 0.0025 C 0.013 0.05 0.04 0.024 0.0011 17.7 0.011 0.045 0.14 0.09 0.18 0.0016 1.19 Cu: 0.18, Mo: 0.2, Sb: 0.02, V: 0.1, Ni: 0.21 D 0.011 0.02 0.05 0.003 0.0028 10.6 0.004 0.055 0.37 0.00 0.00 0.00 1.93 W: 0.2, Co: 0.3, Hf: 0.02, REM: 0.02 E 0.006 0.11 0.09 0.020 0.0008 13.9 0.012 0.042 0.13 0.08 0.06 0.0006 1.17 F 0.001 0.06 0.04 0.011 0.0001 13.4 0.008 0.028 0.01 0.07 0.00 0.00 0.38 G 0.005 0.09 0.11 0.016 0.0021 16.4 0.012 0.038 0.03 0.16 0.00 0.0011 0.78 H 0.012 0.11 0.96 0.023 0.0005 12.2 0.009 0.057 0.05 0.25 0.01 0.00 1.57 La: 0.06, Y: 0.03, Zr: 0.07 I 0.023 0.25 0.21 0.018 0.0011 13.1 0.015 0.065 0.16 0.12 0.00 0.00 1.58 J 0.011 1.03 0.31 0.019 0.0006 13.8 0.011 0.045 0.09 0.03 0.00 0.00 1.89 K 0.012 0.21 1.02 0.016 0.0007 15.2 0.009 0.031 0.14 0.11 0.00 0.00 1.80 L 0.011 0.18 0.15 0.043 0.0008 14.6 0.008 0.075 0.19 0.12 0.00 0.00 1.88 M 0.009 0.17 0.21 0.018 0.0032 11.8 0.013 0.066 0.13 0.21 0.00 0.00 1.53 N 0.008 0.13 0.31 0.019 0.0011 18.2 0.007 0.041 0.13 0.22 0.00 0.00 1.57 O 0.007 0.19 0.15 0.017 0.0021 11.9 0.022 0.038 0.14 0.23 0.00 0.00 1.60 P 0.009 0.26 0.26 0.021 0.0007 14.1 0.009 0.108 0.13 0.24 0.00 0.00 1.73 Q 0.011 0.21 0.31 0.018 0.0012 14.6 0.013 0.038 0.02 0.52 0.00 0.00 1.69 (Note) Nb, Ti, Sn, B: 0.00, not added. Underlined values are shown to be outside the respective ranges of the invention.

Cr-based stainless steel having chemical compositions shown in Table 1 was manufactured through melting. For the Nb, Ti, Sn and B contents in Table 1, the entry “0.0” means that these elements are not added.

The Cr-based stainless steel was hot-rolled by being heated to a heating temperature in a range from 1150 to 1250 degrees C. to manufacture a 5.0-mm-thick hot-rolled steel sheet. The hot-rolled steel sheet was annealed after the hot-rolling in a temperature range from 700 to 900 degrees C. and, subsequent to being pickled, was cold-rolled in a thickness range from 1.5 to 2.5 mm to provide a cold-rolled steel sheet. Conditions for the cold-rolling are shown in Table 2. The cold-rolling was performed by a Sendzimir rolling mill and a tandem rolling mill having respective different work roll diameters. The former used a small diameter roll (60 mm) (indicated as “S” in Table 2) and the latter used a large diameter roll (200 mm) (indicated as “L” in Table 2). The cold-rolled steel sheet was subjected to finish annealing in a temperature range from 920 to 1020 degrees C. and pickling to manufacture a Cr-based stainless steel sheet.

A texture was analyzed using EBSD. A crystal orientation group contributing to hydrogen embrittlement resistance was quantified by displaying a crystal orientation map of the crystal orientation group divided into {211}±10-degree-oriented grains and other regions in the sheet surface. In other words, in a plane in a range of t/8 of a thickness t of the steel sheet from a surface of the steel sheet and parallel to the surface of the steel sheet, a measurement region (sheet width direction: 850 μm, rolling direction: 2250 μm) was subjected to EBSD measurement at a magnification of 100, displayed the crystal orientation map of the crystal grains (i.e., the {211}±10-degree-oriented grains) whose orientation difference between a normal direction of the plane parallel to the surface of the steel sheet and the {211}-plane orientation was 10 degrees or less and also displayed a grain boundary, so that an area ratio and average grain size (in the rolling direction and the sheet width direction) of the crystal grains were measured. Notations shown in the column of “Size” of the {211}±10-degree-oriented grains in Table 2 mean respective sizes in the “rolling direction/sheet width direction”. For some comparatives, measurement results at a thickness center (t/2) were also shown for reference. A site having a difference in a crystal orientation of 15 degrees or more was defined as a grain boundary.

TABLE 2 Cold Rolling {211} ± 10-Degree- Low- Condition Oriented Grain Hydrogen Hydrogen Temperature Rolling Area Size Gaseous Embrittlement Embrittlement Roll Reduction Ratio (Note 2) Pressure Resistance Resistance No Steel (Note 1) % % mm MPa (Note 3) (Note 4) Remarks 1 A L 50 26 0.14/0.13 20 B B Example of the 2 B S 60 13 0.09/0.08 20 A A Invention 3 C S 70 18 0.09/0.07 20 A B 4 D L 50 23 0.13/0.12 20 B B 5 E S 60 17 0.08/0.07 45 B A 6 L 60 10 0.06/0.05 45 A A 7 F S 50 22 0.12/0.11 20 B B 8 L 50 19 0.09/0.08 20 A B 9 S 60 14 0.09/0.07 45 B A 10 L 60  6 0.06/0.04 45 A A 11 H L 50 16 0.08/0.08 20 B A 12 I* S 60 24  0.17/0.15* 20 X X Comparatives 13 J* S 60 26  0.18/0.16* 20 X X 14 K* S 60 27  0.17/0.16* 20 X X 15 L* S 60 23  0.18/0.17* 20 B X 16 M* S 60 22  0.19/0.18* 20 B X 17 N* S 60 32*(24)  0.20/0.19* 20 X X 18 O* S 60 23  0.18/0.16* 20 X X 19 P* S 60 32*(21) 0.14/0.14 20 B X 20 Q* S 60 33*(26)  0.17/0.16* 20 X X (Note 1) Roll: small diameter roll => S, large diameter roll => L (Note 2) {211} ± 10-degree-oriented grain: notations of size are in a rolling direction/rolling vertical direction. (Note 3) Hydrogen embrittlement resistance A: relative tensile strength of 0.98 or more and relative elongation of 0.85 or more B: relative tensile strength of 0.98 or more and relative elongation of 0.75 or more X: one or both of relative tensile strength of less than 0.98 and relative elongation of less than 0.75 (Note 4) Low-temperature embrittlement resistance A: energy transition temperature of −40 degrees C. or less B: energy transition temperature of −10 degrees or less X: energy transition temperature of more than −10 degrees C. (Note 5) *indicates that values are outside the respective ranges defined in the invention. (Note 6) Nos. 17, 19, 20: numerical values in parentheses for an area ratio of {211} ± 10-degree-oriented grain are measured values at a thickness center t/2.

The obtained Cr-based stainless steel sheet was subjected to an evaluation for hydrogen embrittlement and low-temperature embrittlement. As comparative materials, an SUS316L steel sheet (17.5%Cr-12%Ni-2%Mo) and an SUS316 steel sheet (17.5%Cr-10%Ni-2%Mo), each of which had a thickness of 2 mm and was commercially available, were used to evaluate the hydrogen embrittlement resistance.

The hydrogen embrittlement was evaluated according to the following steps.

A tensile test piece (width: 4 mm, length: 20mm) was prepared from a parallel portion. A surface thereof was polished with a dry #600 Emery paper and was subsequently degreased with an organic solvent immediately prior to a tensile test in a high pressure hydrogen gas. As shown in Table 1, the tensile test in the high pressure hydrogen gas was performed at a hydrogen gaseous pressure of 20 MPa or 45 MPa, a test temperature of −40 degrees C. and a strain rate of 10⁻⁵1s. A comparative tensile test was performed in nitrogen (−40 degrees C. and 0.1 MPa). A tensile strength in the high pressure hydrogen gas divided by a tensile strength in nitrogen (0.1 MPa) was defined as a relative tensile strength. A fracture elongation in the high pressure hydrogen gas divided by a fracture elongation in nitrogen (0.1 MPa) was defined as a relative elongation. The hydrogen embrittlement resistance was evaluated using the relative tensile strength and the relative elongation as evaluation indices. Evaluation criteria were as follows. A and B were evaluated to pass.

A: The relative tensile strength of 0.98 or more and the relative elongation of 0.85 or more were satisfied.

B: Except for steel sheets satisfying the above A, the relative tensile strength of 0.98 or more and the relative elongation of 0.75 or more were satisfied.

X: One or both of the relative tensile strength of less than 0.98 and the relative elongation of less than 0.75 were obtained.

Here, when the hydrogen gaseous pressure was 45 MPa and the test temperature was -40 degrees C., the SUS316L steel sheet had the relative elongation of less than 0.75 and thus was evaluated as X. When the hydrogen gaseous pressure was 20 MPa and the test temperature was -40 degrees C., the SUS316 steel sheet had the relative elongation of less than 0.75 and thus was evaluated as X.

The low-temperature embrittlement was evaluated by a Charpy impact test according to JIS Z 2242. A test piece was set to have a V-notch shape (1.5 to 2.5 mm thickness×10 mm width×55 mm length). A test temperature was set to be in a range from −100 degrees C. to a room temperature (20 degrees C.). An energy transition temperature was calculated based on an absorption energy measured in the Charpy test and set to be an evaluation index of low-temperature embrittlement resistance. Evaluation criteria were as follows. A and B were evaluated to pass.

A: The energy transition temperature of −40 degrees C. or less was satisfied.

B: The energy transition temperature of more than −40 degrees C. and −10 degrees or less was satisfied.

X: The energy transition temperature was more than −10 degrees C.

Test results are all shown in Table 2.

Nos. 1 to 11 were each a Cr-based stainless steel sheet having chemical composition and a texture that were within respective ranges of the invention, thereby showing favorable hydrogen embrittlement resistance and low-temperature embrittlement resistance. In particular, Nos. 5, 6, 9 and 10, which were within preferable ranges of the components and the texture, were evaluated as “B” or “A” for the index of the hydrogen embrittlement resistance at a hydrogen gaseous pressure of 45 MPa. The hydrogen embrittlement resistance thereof was superior to that of SUS316L. In Nos. 6, 8 and 10, the {211}±10-degree-oriented grains were reduced using a large-diameter roll. Although having the same chemical composition, the hydrogen embrittlement resistance thereof further improved as compared with that of Nos. 5, 7 and 9.

Nos. 12 to 20 were each a Cr-based stainless steel sheet that did not have chemical composition within the respective ranges of the invention and thus unable to form a texture within the range of the invention, so that one or both of the hydrogen embrittlement resistance and low-temperature embrittlement resistance thereof were deteriorated. In Nos. 17, 19 and 20, the area ratio of the {211}±10-degree-oriented grains at a thickness center was less than 30% but the area ratio thereof in the sheet surface was more than 30%. Accordingly, it has been found that controlling of the area ratio in the sheet surface is important in order to obtain both the hydrogen embrittlement resistance and the low-temperature embrittlement resistance.

In view of the above evaluation results, by having the components and the texture that were within the respective ranges of the invention, each of the Cr-based stainless steel sheets exhibited superior hydrogen embrittlement resistance to that of the commonly available SUS316. It also has been found that each of the Cr-based stainless steel sheets is controlled using the large-diameter roll to have a preferable texture with preferable components, thereby achieving the hydrogen embrittlement resistance superior to that of SUS316L. 

1. A Cr-based stainless steel sheet comprising: 0.020 mass % or less of C; 1.00 mass % or less of Si; 1.00 mass % or less of Mn; 0.040 mass % or less of P; 0.0030 mass % or less of S; 10.0 to 18.0 mass % of Cr; 0.020 mass % or less of N; 0.10 mass % or less of Al; one or both of 0.5 mass % or less of Nb and 0.5 mass % or less of Ti; 0 to 0.3 mass % of Sn; 0 to 0.005 mass % of B; 0 to 1 mass % of Ni; 0 to 1 mass % of Cu; 0 to 1 mass % of Mo; 0.2 mass % or less of Sb; 0 to 0.5 mass % of V; 0 to 0.5 mass % of W; 0 to 0.5 mass % of Zr; 0 to 0.5 mass % of Co; 0 to 0.005 mass % of Mg; 0 to 0.005 mass % of Ca; 0 to 0.020 mass % of Ga; 0 to 0.1 mass % of La; 0 to 0.1 mass % of Y; 0 to 0.1 mass % of Hf; 0 to 0.1 mass % of REM; and a balance consisting of Fe and impurities, wherein a texture in a sheet surface of the Cr-based stainless steel sheet satisfies (i) and (ii) below, (i) in the sheet surface, an area ratio of crystal grains (hereinafter referred to as “{211}±10-degree-oriented grains”) whose orientation difference between a normal direction of a surface of the steel sheet and a {211}-plane orientation is 10 degrees or less is less than 30%, and (ii) for the {211}±10-degree-oriented grains defined in (i), a length in a rolling direction and a length in a sheet width direction are each less than 0.15 mm on average.
 2. The Cr-based stainless steel sheet according to claim 1, further comprising 0.001 to 0.3 mass % of Sn and 0.005 mass % or less of B, wherein the Cr-based stainless steel sheet satisfies Formula (1) below, Si+0.5 Mn+10 P+5 Nb+2 Ti<2.00   Formula (1), where in the formula, symbols of elements indicate contents (mass %) of the respective elements.
 3. The Cr-based stainless steel sheet according to claim 1, further comprising one or more selected from 1 mass % or less of Ni, 1 mass % or less of Cu, 1 mass % or less of Mo, 0.2 mass % or less of Sb, 0.5 mass % or less of V, 0.5 mass % or less of W, 0.5 mass % or less of Zr, 0.5 mass % or less of Co, 0.005 mass % or less of Mg, 0.005 mass % or less of Ca, 0.020 mass % or less of Ga, 0.1 mass % or less of La, 0.1 mass % or less of Y, 0.1 mass % or less of Hf, and 0.1 mass % or less of REM.
 4. The Cr-based stainless steel sheet according to claim 1, wherein the Cr-based stainless steel sheet is used for metals for high pressure hydrogen gaseous equipment. 